In an x-ray tube with a tungsten target (Z = 74) and electrons with 100-keV (or 0.1 MeV) incident energy, only 0.5% of the total energy of the electrons is converted into x-rays.
In the case of a proton or other heavier particles, this type of energy transfer is rare. These are shown by the dotted lines in Figure 6.1. The paths created by high-energy secondary electrons are known as δ-rays. The target electron acquiring this large amount of energy also behaves like a high-energy charged particle, thus creating its own path in the target medium. Whenever a lighter charged particle is deflected at a large angle, the energy transferred to the target electron is also quite large. The path of a heavier particle is more or less a straight line, whereas that of a lighter particle is more tortuous (zig-zag). This leads to a wide variation in the paths of the two kinds of particles (depicted graphically in Fig. Lighter particles in inelastic collisions with the electrons of the target atoms, besides losing energy, tend to be deflected at larger angles than the heavier particles. No, because the manifestation of these interactions on lighter particles-whose masses are of the order of an electron (e.g., e and e +)-and heavier particles-whose masses are equal to or more than that of a proton (e.g., p and α)-is strikingly different. Yes, because inherently the nature of interaction for all charged particles in this energy range is the same (inelastic collisions). Do all charged particles interact in a similar way? The answer is yes and no. The probability of inelastic collisions in general is so high that it does not take a material of much thickness to stop the charged particles completely.ĭifferences Between Lighter and Heavier Charged Particles. For this reason, high-energy radiations are sometimes referred to as ionizing radiations, although excitation events are by no means negligible. In this energy range (10 keV to 10 MeV), ionization events predominate over excitation events. The absorption of energy by the target atom leads to its ionization or excitation. As a result of these pushes and pulls (a sophisticated name for these is inelastic collisions), the charged particle loses some of its energy, which is taken up by the electrons of the target atoms near its trajectory. Through the coulomb forces, it tries to attract or repel the electrons or nuclei near its trajectory. When a charged particle passes through a substance (target), it interacts with the negatively charged electrons and positively charged nuclei of the target atoms or molecules. Principal Mechanism of Interaction (Ionization and Excitation).
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